/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    ASSearch.java
 *    Copyright (C) 1999-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.attributeSelection;

import java.io.Serializable;

import weka.core.Instances;
import weka.core.SerializedObject;
import weka.core.Utils;

/**
 * Abstract attribute selection search class.
 *
 * @author Mark Hall (mhall@cs.waikato.ac.nz)
 * @version $Revision$
 */
public abstract class ASSearch implements Serializable {

    /** for serialization */
    private static final long serialVersionUID = 7591673350342236548L;

    // ===============
    // Public methods.
    // ===============

    /**
     * Searches the attribute subset/ranking space.
     *
     * @param ASEvaluator the attribute evaluator to guide the search
     * @param data        the training instances.
     * @return an array (not necessarily ordered) of selected attribute indexes
     * @throws Exception if the search can't be completed
     */
    public abstract int[] search(ASEvaluation ASEvaluator, Instances data) throws Exception;

    /**
     * Creates a new instance of a search class given it's class name and (optional)
     * arguments to pass to it's setOptions method. If the search method implements
     * OptionHandler and the options parameter is non-null, the search method will
     * have it's options set.
     *
     * @param searchName the fully qualified class name of the search class
     * @param options    an array of options suitable for passing to setOptions. May
     *                   be null.
     * @return the newly created search object, ready for use.
     * @throws Exception if the search class name is invalid, or the options
     *                   supplied are not acceptable to the search class.
     */
    public static ASSearch forName(String searchName, String[] options) throws Exception {
        return (ASSearch) Utils.forName(ASSearch.class, searchName, options);
    }

    /**
     * Creates copies of the current search scheme. Note that this method now uses
     * Serialization to perform a deep copy, so the search object must be fully
     * Serializable. Any currently built model will now be copied as well.
     *
     * @param model an example search scheme to copy
     * @param num   the number of search scheme copies to create.
     * @return an array of search schemes.
     * @throws Exception if an error occurs
     */
    public static ASSearch[] makeCopies(ASSearch model, int num) throws Exception {

        if (model == null)
            throw new Exception("No model search scheme set");

        ASSearch[] result = new ASSearch[num];
        SerializedObject so = new SerializedObject(model);
        for (int i = 0; i < result.length; i++)
            result[i] = (ASSearch) so.getObject();

        return result;
    }
}
